Stereo-video ‘BRUV’ survey of
Rakaumangamanga Rāhui Tapu 2025

Dr. Adam N. H. Smith

Director, Sea Through Science Ltd

What is a ‘Stereo BRUV’?

  • Stereo Baited Remote Underwater Video (SBRUV)
  • Stainless steel frame with two video cameras pointing at a bait canister, with lights and a depth sensor
  • Standard method used globally to monitoring fishes

What is a ‘Stereo BRUV’?

  • After calibration with a specialist cube and software,

What is a ‘Stereo BRUV’?

  • After calibration with a specialist cube and software,
    stereo BRUVs allow for accurate measurements of lengths.

The survey

  • 42 deployments in 2 days (contracted to do 36) in May 2025
  • Four levels of protection

Small snapper and a bronzie

Large snapper

Overall results

  • Observed 38 species from 22 families of fish
  • Average of 9.2 species per deployment
  • Tāmure / snapper were dominant — present at every site, ranging from 15 to 105, average 50
  • Araara / trevally also very widespread
  • Sharks and rays included eagle rays, two bronze whalers, short- and long-tail stingrays, and a hammerhead

Results for tāmure / snapper

Results for tāmure / snapper


Tāmure > 450 cm found only in the area protected since 2010.

Legal-size tāmure found mostly in the rāhui tapu, including newly protected area.

Rapid increase in legal-sized tāmure often observed in no-take areas.

How?

Benefits beyond boundaries

  • Rāhui tapu are a safe haven for BOFFFs — Big Old Fat Fecund Fish
  • Estimated seasonal production of eggs (Crossland 1977, 1981)
    • 250 mm: 80k–300k
    • 500 mm: 4.5M–6M
  • A source of eggs and larvae for surrounding areas